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Caption

Enigma machine rotors. Enigma was a German electromechanical encryption machine used in World War 2. The rotors made an electrical connection between the keyboard for message entry (not seen) and a display (lower right) where the encrypted version of each letter entered would light up. At least one of the rotors turned with each keystroke, meaning that each letter could be enciphered as any other, except itself. The letters on the rotors were used to enter settings that changed daily. Photographed at Bletchley Park, England, where Enigma messages were deciphered.